Signal processing systems have become widespread and include communication systems (such as modems, facsimile, answering machines, and speaker phones), audio systems, and multimedia systems (such as digital video disk, or "DVD"). Signal processing devices can be either internal or external to a host computer, such as a "PC," and typically interface with the host computer as well as with the external world, e.g., via a telephone network, audio speakers, or a video screen.
Most signal processing systems are function specific and include software and hardware dedicated to that particular function. For instance, in a signal processing system that performs a modem function, the system will include specific hardware for interfacing to a telephone network, including analog front end (AFE) hardware and data access arrangement (DAA) hardware, as well as a considerable amount of program code stored in the system and specific for modem communications. Such program code is often stored in the system on a Read Only Memory (ROM), which can be written to only once and cannot be changed once written. Still, despite their differences in functionality, many signal processing systems utilize similar hardware elements, particularly for digital signal processing, such as DSPs (digital signal processors) and microprocessors. Yet, because of analog hardware considerations, particularly to interface to the outside world, and because the software differs, each digital signal processing device must be purchased separately.
Moreover, even within a single type of signal processing system, standards are not constant either geographically or temporally. For instance, an international business traveler using a laptop computer cannot use in Europe the same modem he purchased in the United States. In fact, because even communication standards vary from country to country in Europe, the international traveler may need to carry several modems, each complying with a different country's communication standards, in order to communicate using a modem at each destination. Further, each time a different modem is to be used, the host system will have to be notified and often will need to be reconfigured to utilize the modem.
In addition, signal processing technology is progressing at a rapid rate. Even making relatively simple updates to the protocols used by signal processing systems, e.g., modems, is difficult because program code is usually unchangeable as being encoded in ROM. Thus, for consumers to take advantage of the newest technology, they generally have to replace their old systems. While recently, some modems have been developed with a degree of upgradability, e.g., 36 Kbps modems to 56 Kbps, because of the fixed nature of their hardware and software, most modems will have to be completely replaced to allow use of the most recent technology. In fact, when new communication technologies are widely available to consumers, including ISDN modems, DSL modems, cable modems, and wireless modems, a consumer wishing to utilize one of these new technologies will need to purchase a new device.
Some companies have recognized in the modem arena that, for instance, the processing of modem data in various countries is the same, and only the network interface differs. These companies have developed communication adapters (primarily line conditioning and media conversion circuitry, e.g., DAA circuitry) that can be selectively coupled with their modem and that supply the necessary hardware and software configuration information to the modem in order to allow the modem to engage in any necessary signal processing to comply with the standards of various countries. These adaptors themselves perform no signal processing functions and in fact, the core software on the base system remains the same. The signal processing system itself can be used to perform no other function than that of a modem.
Thus, despite many commonalities among systems, a consumer who wants to be able to perform two distinct signal processing functions, or even upgrade his present signal processing system, the consumer must generally purchase two complete signal processing systems. Each of these systems will be dedicated to a specific signal processing function and technology standard.
Therefore, a signal processing system that allowed easy adaptability to a variety of signal processing functions, that would reduce signal processing system costs overall to the consumer, and that would allow upgrades as well as functional changes, would represent an advancement in the art.